NO162244B - SILICONE-CONTAINING POLYMERS WITH HIGH OXYGEN PERMEABILITY AND PROCEDURES FOR PREPARING IT. - Google Patents

Abstract

Clear, strong, crosslinked polymers are described, which are obtained by copolymerization of (A) 8-70% of a linear or branched polysiloxane of 400-100,000 molecular weight (MW) containing at least two terminal or pendant, polymerizable, vinyl groups per each 5000 MW unit of polysiloxane and which are attached to the polysiloxane through at least two urethane, thiourethane, urea or amide linkages and (B) 30-92% of a mono- or divinyl compound or a mixture of such monomers consisting of 85 to 100% of water insoluble monomers. These polymers are useful in the preparation of hard or soft contact lenses.

Description

The invention relates to clear, strong, cross-linked polymers which are obtained by copolymerization of (A) a straight-chain or branched polysiloxane macromer containing at least 2 terminal or pendant polymerizable vinyl groups bound to the polysiloxane by means of a urethane, thiourethan, urea or amide group, and (B) a vinyl or divinyl monomer or mixtures of monomers, which monomers consist of 85-100% water-insoluble monomers, which polymers are suitable in the manufacture of soft or hard contact lenses, especially the hard lenses .

Contact lenses are divided into two main categories, usually called "hard" and "soft", but which are better distinguished by the way they are adapted to the eye. Rather, hard contact lenses are loosely adapted to effect exchange of tear fluid between the lens and cornea, which is accomplished by their "highchair" motion, whereby they continuously pump tear fluid out of the space between the lens and the surface of the eye. Such tear fluid yield is the only means by which all important oxygen is supplied to the cornea of the wearer of conventional hard contact lenses made of polymethyl methacrylate (PMMA).

Although hard PMMA lenses are, at least initially, uncomfortable and irritating to the wearer due to the blinking eyeball hitting a hard edge, they are nevertheless popular because they can be manufactured with great precision by turning and polishing. This is particularly important for the correction of astigmatism with lenses of asymmetrical design. Another advantage is that they are very easy to keep clean, whereby no sterilization is needed.

Soft contact lenses, on the other hand, adhere closely to the cornea and are therefore much more comfortable for the wearer, as they only allow limited tear fluid yield, they must have a sufficiently high oxygen permeability to prevent eye damage even if they have been worn for only a few hours.

In all commercial soft contact lenses, this C₂ permeability is a function of their water content, which is a property of hydrogels. In addition, water acts as a softening agent, giving the lens its softness and the necessary hydrophilic properties that enable it to float and rotate on the cornea, rather than sticking to it. Adhesion to the cornea is the main problem with hydrophobic, soft lenses, such as the otherwise very attractive silicone-rubber lenses. Although hydrogel soft lenses represent advances in comfort, compromises are made in terms of precision, as some distortion due to water swelling is inevitable, as they are prone to rotating on the eye and, in addition, astigmatism is a much more difficult problem to solve . Moreover, protein adsorption and disinfection are the main problems and the increase in comfort is largely balanced by greater difficulty in more complicated procedures for lens cleaning.

The next important development in contact lens technology was the production of lenses that could be worn continuously, day and night, for up to several weeks. Oxygen permeability of the lenses must be increased many times for this purpose, because in the closed eye position during sleep, the corneas are supplied with all the oxygen from the blood-transmitting eyelid. Among the various problem solutions that have not succeeded satisfactorily in this respect are: (-]) hydrogels with a high water content of up to 70% water, their disadvantage is mechanical weakness and because of this they must be produced thicker and (^- permeability is therefore reduced, and (B) silicone rubber lenses which have completely failed due to their extreme water repellency, stick like a suction cup to the cornea and lead to serious eye damage Attempts to make the surface of the silicone rubber lenses sufficiently hydrophilic to prevent this, has not been too successful, mostly because the treated surface area is too thin to be permanent, eg the lenses manufactured by DOW CORNING under the trade names "SILICON" and "SILSOFT" are treated to form a -Si-OH surface layer which, however, is so thin that it easily wears off, especially on a hard lens. It is an object of the invention to provide a silicone-containing, hard lens if ove rflate is permanently wettable. Another disadvantage of 100% silicone rubber contact lenses is the difficulty with which the edges can be finished and polished, and thus made comfortable for the wearer. this is an inherent problem with all rubbery materials. It is a further object of the invention to provide the silicone-containing polymer material which varies from "soft" to "hard" - according to contact lens terminology - but all of which are easily polishable.

Recent examples of silicone-containing hydrophobic polymers are described in US-PS 4,153,641, 4,189,546 and 4,195,030 and they consist of polymerized or copolymerized polysiloxane or polyparaffin-siloxane diacrylates and high molecular weight methacrylates. The resulting polymers are hydrophobic. US-PS 4,217,038 describes a surface treatment for obtaining hydrophilic surfaces. Other contact lens materials containing polysiloxanes are described in US-PS Nos. 4,208,362, 4,208,506, 4,254,248, 4,259,467, 4,277,595, 4,260,725 and 4,276,402. All these patents are based on bis-methacrylate esters of straight-chain polysiloxanediols. Because of the soft nature of straight-chain polysiloxanes, they are not suitable for making the hard, rigid materials necessary for a hard contact lens. US

PS No. 4,136,250 describes, in addition to the above-mentioned bis-methacrylates of straight-chain polysiloxane diols, also bis- and tris-methacrylates of diols and triols in which the functional groups are pendant, not terminal,

to the main polysiloxane chain, and also compounds which are connected to the polysiloxane by bis-ureane linkages. However, all compositions are hydrogels and as such are only suitable for soft contact lenses.

A rigid silicone-containing hard lens is described in US-PS r. 4,152,508 and it consists of a copolymer of an oligo-siloxanyl-alkyl acrylate with various comonomers, such as dimethyl itaconate and methyl methacrylate. Although it is claimed

«.,,.- ,n-10 cm3(STP).cm . , permeabilities of 3-50x10 -H—; =— do the high amounts of oligosiloxane-substituted methacrylate (>40%) which

not necessary to get G^ permeabilities higher than 9, the polymer at the same time too soft to be suitable as a hard lens. Only if the Si monomer components are less than 25% of the polymer, the polymer hardness is sufficiently high for hard contact lens use. As the siloxane content also has an adverse effect on the wetting ability, it is naturally an advantage to use as little Si in the polymer as possible, just enough to obtain the required G^ permeability.

Siloxanurethane acrylate compounds suitable for the preparation of coating compositions for radiation curing are described in US-PS No. 4,130,708. These siloxanurean acrylate compounds can be mixed with other ingredients commonly found in coating compositions and radiation cured with UV light. The use of such materials for contact lenses is neither described nor suggested in this patent. The coating compositions described in the patent do not include any hydrophilic monomer components.

GB-PS No. 2,067,213 also describes siloxanurethane acrylate compounds which are suitable for the production of photocurable coating compositions. The use of such materials for contact lenses is not described. The coating compositions described in this patent do not include any hydrophilic monomer components, nor are the hydrophobic comonomers described in this invention.

US patent no. 4,341,889 covers cross-linked polymers consisting of a) polysiloxanes with polymerizable terminal groups,

b) tert-butylstyrene and c) hydrophilic vinyl monomers. Thereby means the bivalent group R which in the polysiloxanes a) connects

silicon and the polymerizable terminal groups always the alkylene or the arylene. The use of diisocyanate is not mentioned above, whereas in the present invention diisocyanate is essential.

It is known that SiO(CH3)2 is a more effective oxygen transmitter if it is present in the form of a siloxane polymer than if it is only part of a low molecular weight: side group. However, the long polysiloxane chains present in compositions of US-PS No. 4,153,641 and related patents greatly reduce stiffness, leading to rubbery and soft materials. Moreover, their compatibility with such unrelated polymers as polymethacrylates is poor due to phase separation, typical of mixtures of high molecular weight polymers, leading to more or less opaque products.

It has now been unexpectedly discovered that if polyfunctional hrtvmolecular polysiloxanes whose equivalent weight is not greater than e.g. and which are bound to at least two terminal or pendant polymerizable vinyl groups of bis-urethane linkages are mixed in a cross-linked vinyl copolymer, hard, rigid and clear products are obtained which have excellent O2 permeability, up to 4 times higher than that of the best previously known composition, and which, even with a siloxane content of >50%, is sufficiently rigid to meet the requirements for a hard contact lens. It has further, very unexpectedly, been found that siloxane-containing polymers according to the invention can be produced with better wettability than conventional PMMA hard lenses, despite their high polysiloxane content.

The preferred polysiloxane macromers for synthesizing hard contact lens materials are those which contain (a) at least one urethane linking group per 12 fSiO(CH3)24 units; (b) containing at least two polymerizable vinyl groups attached pendantly to the polysiloxane backbone and therefore containing at least two terminal fSitCH^)-^ units; and (c) contains urethane groups derived from bulky, cycloaliphatic diisocyanates. The preferred comonomers which can form a connection with the polysiloxane macromers,

are acrylates and methacrylates which, when polymerized with themselves, give hard homopolymers with a high glass transition

temperature, such as methyl methacrylate, isopropyl, isobutyl, tert.butyl, cyclohexyl or isobornyl methacrylate.

Although the invention is primarily aimed at hard contact lens materials, it has also been found that clear, strong but rubbery polymers can be produced. Such polymers which are suitable for various purposes such as biocompatible implants, bandages for wound treatment or as soft contact lenses, are thus another purpose of the invention.

It is thus within the scope of the invention to use comonomers which will give strong, flexible and rubbery polymers.

The invention relates to polymer which is suitable for the production of contact lenses and which is characterized in that it consists of a cross-linked polymerization product of A) from 15 to 60% by weight of a linear or branched polysiloxane macromer with a molecular weight from 400 to 100,000, measured by end group analysis or gel permeation chromatography,

in that the macromer contains at least two terminal or pendant polymerizable olefinic groups per each 5,000 molecular weight units of polysiloxane, the groups being connected to the polysiloxane with at least two urethane, thiourethane, urea or amide bonds, the macromer having the structure A1 or A„

in which is a linear or branched alkylene group with 2-6 carbon atoms or a polyoxyalkylene group of structure G

wherein R3 is hydrogen or methyl, and n is an integer from 1-50,<R>2, Ra, Rb, Rc, Rd, Re. Rf. Rg»»h»Ri'Rj°SRkmeans methyl, X^and X2 are whole numbers from 1-500, with the proviso that the sum of X^plus X2 is 7 to 100, y^means 0 to 14 and Y2means 1 to 13, with provided that the ratio of X} + X2or X^+ X2 is not greater than 70,

Y1+ 2 Y2+ 1

X is a diradical of formula C

wherein Z 1 is oxygen, sulfur or NR 5 , and R 5 is hydrogen or lower (C 1 -C 4 ) alkyl, Z 2 is linked to R 1 ;

and R 4 is the divalent radical formed by removing NCO groups from an aliphatic or cycloaliphatic diisocyanate;

Y is a group with formula

wherein R f 1 is hydrogen, methyl or -COOR 5 , wherein R 5 is hydrogen or lower (C 1-4 )-alkyl; Z2 means oxygen or -NR5-, and R7 and Rg are linear or branched alkylene with 2-10 carbon atoms,

and of from 85 to 40 wt-£ of a vinyl monomer (B) "consisting of a mixture of a water-soluble monomer B2

and a water-insoluble monomer, or a water-insoluble monomer Bjeller a mixture thereof, the monomers being monoolefinic, or a diolefinic monomer Bxor a mixture thereof, or a mixture of the monoolefinic and diolefinic monomers with from 85 to 100% by weight of the total monomers which water insoluble,

where the monoolefinic monomers B^ are selected from acrylates or methacrylates with the formula CH2=CR3C00Ri2» acrylamides or methacrylamides with the formula CH2=CR3CONHRi2» maleates or fumarates with the formula Ri20C0CH=CHC00Ri2» itaconates with the formula<R>i200CC:(=CH2)CH2C00R12, vinyl esters with the formula R12C00CH=CH2 or vinyl ethers with the formula C02=CH0R12, where R3 means hydrogen or methyl, and R^2 is a linear or branched aliphatic, cycloaliphatic or aromatic alkyl group with from 1 to 21 carbon atoms, and which may contain ether or thioether bonds or -CO group, or means a heterocyclic substituted alkyl group containing oxygen, sulfur or nitrogen atoms, or a polypropylene oxide or poly-n-butylene oxide group with from 2-50 recurring alkoxy units or means perfluorinated alkyl groups with from 1-12 carbon atoms , or means acrylonitrile, styrene or cx-methylstyrene, and the olefinic monomers B2 are chosen from acrylates or methacrylates with the formula CH2=CR3C00R^3, acrylami where or methacrylamides of the formula CH2=CR3C0NHRi4or CCH2=CR3C0N(R5)2, maleates or fumarates of the formula R130C0CH=CHC00R13, vinyl ethers of the formula CH2=CH0R13, or N-vinyllatamers, in which R3 is hydrogen or methyl, R5 is hydrogen or lower (Cq- 4)-alkyl, R 3 is a hydrocarbon residue with 1-10 carbon atoms, substituted with one or more water-solubilizing carboxy, hydroxy or tert.-amino groups, or a polyethylene oxide group with from 2 to 100 recurring units, and R 14 has the same meaning as R^3 or R5, and the diolefinic monomers Bxer selected from acrylates or methacrylates of allyl alcohol, diacrylates or dimethacrylates of linear or branched alkylene glycol with 2-6 carbon atoms, of poly(ethylene oxide) glycol, of poly(propylene oxide) glycol, of poly( n-butylene oxide)glycol, av

thiodiethylene glycol, of neopentylene glycol, of trimethylolpropane or of pentaerythritol, or the reaction product formed by reacting 1 mol of a di- or tri-isocyanate with the structure OCN-(NCO)v, where R4 has the above meaning, and v means 1 or 2, with 2 or 3 moles of a hydroxyalkyl acrylate or methacrylate.

The compounds with structures (A^) and (A2>) are thus polysiloxanes connected by a diisocyanato bond to vinyl groups which can be of acrylic or methacrylic, fumaric, or itanone (Y structure D), allyl (E) or vinyl ether (F) nature .

Preferred embodiments of the present invention have

= the alkylene with 3 or 4 carbon atoms, and x1 + x2 = 10 to 100,

Y1=0 to 2,

y2=1 to 3,

X = -Z1-CO-CH-R4-NH-CO-

where Z^= oxygen or -NH-f,

R^= diradical of aliphatic or cycloaliphatic diisocyanate with 6-10 carbon atoms, Y = of structure D, in which'

Rg = hydrogen,

R 8 = ~CH 2 CH 2 ~

and

Z2= oxygen or

Most preferred embodiments comprise the polysiloxane with structure: (A2):

r4= diradical of isophorone diisocyanate,

Zl'22 = oxy9ene/°9

Y2=1 or 2.

Included among the useful monomers are: methyl-;

ethyl-; propyl-; isopropyl-; butyl-; isobutyl-; tert.-buty1-;

ethoxyethyl-; raethoxyethyl-; benzyl-; phenyl-; cyclohexyl-;

trimethylcyclohexyl-; isobornyl-; dicyclopentadienyl-;

norbornylmethyl-; cyclododecyl-; 1,1,3,3-tetramethylbutyl-;

n-butyl-; n-octyl-; 2-ethylhexyl-; decyl-; dodecyl-; tri-decyl-; octadecyl-; glycidyl-; ethylthioethyl-; furfuryl-;

hexafluoroisopropyl-; 1,1,2,2-tetrahydroperfluorododecyl-;

tri-, tetra- or penta-siloxanyl propyl acrylates and methacrylates, as well as the corresponding amides; N-(1,1-dimethyl-3-oxobutyl)acrylamide; mono- and dimethyl fumarate, maleate and itaconate; diethyl fumarates; isopropyl and diisopropyl pylfumarate and itaconate; mono- and diphenyl and methylphenyl fumarate and itaconate; methyl vinyl ether and methoxyethyl vinyl ether;

vinyl acetate, vinyl propionate, vinyl benzoate, acrylonitrile,

styrene and alpha-methylstyrene.

)

5

To achieve the high clarity required for contact lens applications, it is particularly useful to use comonomers or comonomer mixtures whose corresponding polymers exactly match the solubility parameter (6) and/or refractive index (RI) of the values for polydimethylsiloxane (5=15; RI=1.43). Such monomers are e.g. isobornyl, methacrylate, tert-butyl methacrylate and mixtures of hydrocarbon methacrylates (RI 1.46) with fluorine containing monomers such as hexafluoroisopropyl methacrylate, trifluoroethyl methacrylate; 1,1,2,2-tetrahydroperfluoroalkyl methacrylate or 4-thia-6-perfluoroalkylhexyl methacrylate, where alkyl or a carbon chain of 5-12 C atoms (RI's of 1.38-1.40) ( 6 <15). Moreover, monomers containing perfluoroalkyl groups clearly increase the oxygen permeability of the polymers in a synergistic manner with polysiloxane, as such they are therefore particularly preferred comonomers.

For the production of hard lenses, the preferred comonomer content is 50-85% by weight of the total polymer, whereby preferred comonomers are methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate or hexafluoroisopropyl methacrylate or mixtures thereof.

The most preferred comonomer is methyl methacrylate, isobornyl methacrylate, isopropyl methacrylate, isobutyl methacrylate or cyclohexyl methacrylate, or mixtures thereof. Most preferred are also mixtures of methyl methacrylate and/or

isobornyl methacrylate with 1-25% by weight of the total monomer of a short-chain cross-linking agent such as neopentylene glycol diacrylate, ethylene glycol dimethacrylate or the reaction product of 1 mol of isophorone diisocyanate and 2 mol of 2-hydroxyethyl methacrylate.

Another most preferred comonomer system for making hard lenses is vinyl acetate/dimethyl maleate (2/1 to 5/1 molar ratio) plus a preferred methacrylate monomer

as stated above.

For the production of soft lenses, the preferred comonomer is 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-butyl acrylate, n-butyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-decyl acrylate n-decyl methacrylate, perfluoroalkyl (Cr-C,n) substituted alkyl acrylate or methacrylate or mixtures thereof.

The contact lenses made from polymers according to the invention are filler-free, hydrolytically stable, biologically inert, transparent and sufficiently permeable to oxygen to allow the transport of sufficient oxygen to meet the needs of the human cornea.

The water-soluble vinyl monomer (B2) which is suitable for the present invention is preferably acrylates and methacrylates with the general structure:

R,, is a hydrocarbon residue with 1-10 carbon atoms substituted

with one or more water-soluble groups such as car-

5 boxy, hydroxy or tert.-amino, or a polyethylene oxide group with from 2-100 repeating units, or a group containing sulphate, phosphate, sulphonate or phosphonate groups.

) Acrylamides and methacrylamides with structure

> wherein R,, is R^ or R^;

Acrylamides and methacrylamides with structure

Structured maleates and fumarates Structured vinyl ethers

N-vinyi-±aKtamates, such as N-vinyi-^-pyrroxiaone,

Included among the applicable water-soluble monomers are:

2-hydroxyethyl-; 2- and 3-hydroxypropyl-, 2,3-dihydroxy-

in propyl-, polyethoxyethyl-; and polyethoxypropyl acrylates

and methacrylates as well as the corresponding acrylamides and methacrylamides. Sucrose, mannose, glucose, sorbitol acrylates and methacrylates.

in

i Acrylamide and methacrylamide; N-methylacrylamide and methacrylamide, bisacetone-acrylamide; 2-hydroxyethyl acrylamide; dimethylacrylamide and methacrylamide; methylacrylamide and methacrylamide.

N,N-dimethyl and N,N-diethyl aminoethyl acrylate and methacrylate

) as well as the corresponding acrylamides and methacrylamides;

N-tert-butyl aminoethyl methacrylate and methacrylamide; 2- and' 4-vinylpyridine; 4- and 2-methyl-5-vinylpyridine; N-methyl-4-vinyl-piperidine; 1-vinyl- and 2-methyl-1-vinyl-imidazole;

dimethylallylamine and methyldiallylamine. para- and ortho-

j aminostyrene; dimethylaminoethyl vinyl ether; N-vinylpyrrolidone; 2-pyrrolidinoethyl methacrylate.

Acrylic and methacrylic acid; itakon-; cinnamic, crotonic, fumaric, maleic acids and lower hydroxyalkyl mono- and diesters thereof, such as 2-hydroxyethyl and di(2-hydroxy)ethyl fumarate,

-maleate and itaconate, and 3-hydroxypropyl-butyl-fumarate,

and di-polyalkoxyalkyl fumarates, maleates and itaconates.

Maleic anhydride; sodium acrylate and methacrylate, 2-methacryloyloxyethylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-phosphate ethyl methacrylate, vinylsulfonic acid, sodium vinylsulfonate, p-styrenesulfonic acid, sodium p-styrenesulfonate, and allylsulfonic acid.

Also included are the quaternized derivatives of cationic monomers: obtained by quaternization with selected alkylating agents such as halogenated hydrocarbons, such as methyl iodide, benzyl chloride or hexadecyl chloride; epoxides such as glycidol, epichlorohydrin, ethylene oxide; acrylic acid, dimethyl sulfate;

methyl sulfate; propane sultone.

A more complete list of water-soluble monomers suitable in connection with the present invention can be found in: R.H. Yocum, E.B. Nyquist, Functional Monomers; Vol. 1, pages 424-440 (YÆ.. Dekker, N.Y. 1973).

Preferred monomers are:

(B^) == methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, t-butyl and, isobutyl methacrylate, isopropyl methacrylate, hexafluoroisopropyl methacrylate.

(B^) = 2-hydroxyethyl methacrylate; N,N-dimethylacrylamide;

acrylic and methacrylic acid, N-vinyl-2-pyrrolidone.

A wide range of divinyl compounds can be used in addition to the monovinyl compounds. From 1-25% by weight of the total monomer B can really be a diolefinic monomer (B^). Examples of diolefinic monomers are: Allyl acrylate and methacrylate, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and generally polyethylene oxide glycol diacrylates and dimethacrylates; 1,4-butanediol-

and poly-n-butylene oxide glycol diacrylates and dimethacrylates; propylene glycol and polypropylene oxide glycol diacrylates and dimethacrylates; thiodiethylene glycol diacrylate and dimethacrylate; di(2-hydroxyethyl)sulfone diacrylate and dimethacrylate; neo-pentylene glycol diacrylate and dimethacrylate; trimethylolpropane-tri and tetraacrylate; pentaerythritol tri and tetraacrylate; divinylbenzene; divinyl ether; divinyl sulfone; disiloxanyl bis-3-hydroxy-propyl diacrylate or methacrylate and related compounds.

Bisphenol A diacrylate or dimethacrylate, ethoxylated bisphenol A diacrylate or dimethacrylate; methylene bisacrylamide or methacrylamide, dimethyl bisacrylamide or methacrylamide; N,N'-dihydroxyethylene bisacrylamide or methacrylamide; hexamethylene bisacrylamide or methacrylamide; decamethylene bisacrylamide or methacrylamide; allyl and dialkyl maleate, triallyl melamine, diallyl itaconate, diallyl phthalate, triallyl phosphinite, polyallyl sucrose, sucrose diacrylate, glucose dimethacrylate; also unsaturated polyesters, such as poly-(alkylene glycol ^ maleate) and poly(alkylene glycol fumarates), such as poly(propylene glycol maleate) and poly(polyalkylene oxide glycol maleate).

Also useful as cross-linking agents are the reaction products obtained by reacting 1 mol of di- or tri-isocyanate of structure OCN-R^-(NVO)^, in which R^ is as described below, with 2 or 3 mol of hydroxyalkyl acrylate or methacrylate, or a hydroxyalkyl vinyl ether or allyl alcohol, or N-tert-butylaminoethyl methacrylate, or bis-hydroxyethyl maleate or any of the compounds listed below which contain active hydrogen.

The preferred diolefinic monomer (Bx) is the acrylate or methacrylate of allyl alcohol, of a straight-chain or too branched alkylene glycol with 2-6 carbon atoms, of poly(ethylene oxide) glycol, of poly(propylene oxide) glycol, of poly(n-butylene oxide) glycol, of thiodiethylene glycol, of neopentyl glycol, of trimethylolpropane, or of pentaerthritol; or the reaction product obtained by reacting 1 mol of a di- or tri-isocyanate with the structure OCN-R4~(NCO) , where R. is as defined above and v is 1 or 2, with 2 or

3 moles of a hydroxyalkyl acrylate or methacrylate.

A most preferred difunctional comonomer (Bx) is 1 to 25% by weight of the total monomer of neopentylene glycol diacrylate, the reaction product of 1 mol of isoporone diisocyanate and 2 mol of 2-hydroxyethyl methacrylate, or ethylene glycol dimethacrylate.

The monomers can be used alone or in combination with each other whereby the necessary attention must be paid to their copolymerization parameters to ensure that arbitrary copolymerization does not take place. Moreover, if the polymers are to be used for contact lenses, it is important for the selection of a suitable monomer combination that this has a high degree of clarity and is colourless.

A preferred embodiment of the present invention is a polymer where the component A is a polysiloxane with structure A^ or A.,, R-^ is the alkylene with 3 or 4 carbon atoms, -n.

X is -Z1-CONH-R4-NHCO- where ZL -is -0- or -NH- and

R4. is a diradical of an aliphatic or cycloaliphatic diisocyanate of 6 to 10 carbon atoms, and Y is

wherein Rg is hydrogen, Rg is ethylene, and

' z2 is -0- or -NH(CH3)3~, and component B in-

contains from 1-25% based on total monomer of a diolefinic monomer (Bx) which is the acrylate or methacrylate of allyl alcohol, of a straight-chain or branched alkylene glycol with 2-6 carbon atoms, of poly(ethylene oxide) glycol, of poly-(propylene oxide) glycol, of poly(n-butylene oxide) glycol, of thiodiethylene glycol, of neopentylene glycol, of trimethylolpropane, or of pentaerythritol; or the reaction product obtained by reacting 1 mol of a di- or tri-isocyanate with the structure OCN-R^-(NCO), where is as defined above and v is 1 or 2, with 2 or 3 mol of a hydroxyalkyl acrylate or methacrylate.

Polyfunctional polysiloxanes, suitable as starting materials for the macromer (A), are of structures I or II

in which:

Rl'R2'Ra'Rb'Rc'Rd'Re'Rf Rg'Rh'Ri'Rj'Rk'Zl'

x^, * 2> vi°9^2er SOItl described above.

Diisocyanates suitable for the formation of the prepolymer intermediate are aliphatic, cycloaliphatic or aromatic polyisocyanates with structures:

and includes: ethylene diisocyanate, 1,~2-diisocyanate propane, 1,3-diisocyanate propane, 1,6-diisocyanate hexane, 1,2-diisocyanate cyclohexane, 1,3-diisocyanate cyclohexane, 1,4-diisocyanate cyclohexane, o-diisocyanatebenzene, m- diisocyanatebenzene, p-diisocyanatebenzene, bis(4-isocyanatecyclohexyl)methane, bis(4-isocyanate cyclohexanyl)methane, bis(4-isocyanatephenyl)methane, toluene diisocyanate, 3,3-dichloro-4,4'-diisocyanateb.if f enyl, 1,5-diisocyanatephthalein, hydrogenated toluene diisocyanate,

1-isocyanatemethyl-5-isocyanate-1,3,3-trimethylcyclo-

in hexane (= isophorane diisocyanate), 1,6-diisocyanate-2,24-(2,4,4)-trismethylhexane, 2,2'-diisocyanate diethyl fumarate, 1,5-diisocyanate-1-carboxypentane,

1„,2-, 1,3-, 1,5-, 1,6-, 1,7-, 1,8-,

2,7- and 2,3-diisocyanate naphthalene; 2,4- and 2,7-diisocyanate

in 1-methylnaphthalene; 1,4-diisocyanate-methyl-cyclohexane; 1,3-diisocyanate-6(7)-methyln-aphthalene; 4,4'-diisocyanate biphenyl;

4,4'-diisocyanate-3,3α-dimethoxy-bisphenyl; 3,3'- and 4,4'-diisocyanate-2,2<1->dimethyl biphenyl; Bis-(4-isocyanatephenyl)ethane;

bis(4-isocyanatephenyl)ether.

)

The diisocyanates can be used alone or in combination with each other.

Active hydrogen-containing monomers suitable for terminating 5 the polysiloxane-polyisocyanate include compounds with the structure:

in which R^, Rg, Rg, and Z' are as described above and as such are active hydrogen-containing acrylates, methacrylates, fumarates, maleates and the corresponding amides, such as: 2-hydroxyethyl-; and 3-hydroxypropyl-; 2,3-dihydroxypropyl-; polyethoxyethyl-; polyethoxypropyl-; polypropoxy-propyl-1-acrylates and methacrylates as well as the corresponding acrylyl and methacrylamides; 2-hydroxyethyl oq bis(2-hydroxyethyl)fumarate, hydroxypropylbutyl fumarate; N-(2-hydroxyethyl)maleimide and N-(2-hydroxyethoxyethyl)maleimide; tert-butylaminoethyl methacrylate, pentaerythritol mono-,

and diacrylate.

Other suitable classes of compounds are allyl monomers such as allyl alcohol and methallyl alcohol and diallylamine;

and

vinylethanes with the structure

where R^ is as described above, e.g. 4-hydroxybutyl vinyl ether.

A list of suitable monomers in connection with this invention can be found in R.H. Yocum, E.B. New Guist; Functional Monomers, vol. 1, pages 424-440 (M. Dekker, N.Y. 1973).

The polysiloxane-polyisocyanate prepolymer can also be end-capped by unsaturated acids using a base or metal catalyst and result in an amide bond with the development of CC>2 • Suitable acids include: acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid.

The monomers and B^, the diisocyanates and the polyfunctional polysiloxane starting materials for A are largely commercially available products.

The polysiloxane macromers are usually obtained by a 2-step synthesis from the corresponding polyfunctional polysiloxanes. These are in the most preferred case diols or polyols, but can also be amino-functional or mercapto-functional polysiloxanes. As a first step, the polysiloxane is reacted, either in bulk or in solution, with a given amount of a di- or tri-isocyanate in the presence of any of the conventional catalysts. This catalyst can be compounds containing tertiary amino groups such as triethylamine, pyridine or diamino-bicyclooctane, or metal-based lysators such as dibutyl tin dilaurate or tin octoate. The reaction is carried out either at ambient temperatures or elevated temperatures under a dry nitrogen atmosphere and can be followed conventionally with an NCO titration or IR analysis. In the case of diisocyanate, the % NCO decreases to a calculated value of the initial value, and the first stage reaction product consists of a polysiloxane diisocyanate. The molar ratio of OH to NCO groups during the first reaction step can be 1:1.5 to 1:3 and is preferably in the range of 1:2.05-1:2.1.

The second stage of the turnover consists of closing

of this polyisocyanate with a hydroxy- or amino-functional vinyl compound, most commonly with 2-hydroxyethyl methacrylate. It is advisable to use at least a small excess of the end-terminating monomer, typically a mole ratio of OH, SH, NH/NCO of 1.05/1 or greater.

As it is a preferred practice to incorporate smaller amounts of a water-soluble monomer in the final polymer in order to achieve good wetting properties, a larger excess of the hydroxy- or amino-functional monomer is not unfavorable. The reaction proceeds at ambient or elevated temperatures over a period of several hours, where an additional catalyst is not necessary. As usually no inhibitors are present, it is important to have an oxygen-free, nitrogen atmosphere. The completion of the reaction is easily determined by IR spectroscopy where -NCO groups are checked.

Sometimes it is convenient, e.g. in cases of very

high viscose material, to carry out the second step of the macromer synthesis in a monomer solution corresponding to the desired final polymer composition. Although it is preferred to react one equivalent of reactive polysiloxane with close to two equivalents of diisocyanate and thereby obtain an isocyanate-terminated polysiloxane, due to the laws of polycondensation kinetics, a certain amount of chain-extended product can be obtained, in which the end-terminated polymer contains two polysiloxane chains bound of a diisocyanate unit,

and can be analyzed, e.g. by gel permeation chromatography.

It is also within the scope of the present invention to use as polysiloxanes for polymers formed from polysiloxanes with structures I and II by chain-extending reactions which are usually used by those skilled in the field of polycondensation, especially polyurethane, chemistry. Such chain extensions can be carried out e.g. by polycondensation of the above-mentioned polysiloxanediols, dithiols or diamines with: diacid chlorides or anhydrides or dianhydrides, such as teraphthaloyl chloride, adipic acid dichloride, maleic anhydride, phthalic anhydride or benzophenone tetracarboxylic acid and dianhydride, with diisocyanates with structures as mentioned above,

in which case the synthesis step for the preparation of the NCO-terminated macromer as described is easily carried out with less than a 2:1 excess of NCO relative to -OH, -SH or -NH2 groups, likewise the NCO-terminated prepolymers, formed before the end-end-end,

is carried out with the hydroxy-vinyl compounds - chain extension with diols or diamines according to the known technique from polyurethane technology, with, for example, ethylene glycol, propylene glycol, butanediol, hexanediol, polyetherdiols containing ethylene oxide, propylene oxide or n-butylene oxide repeating units? polyester diols, ethylenediamine, hexanediamine and diprimary or di-secondary amines in general, including diamines derived from polyalkylene oxides. Depending on the degree of these chain extension reactions of additional amide, urethane or urea groups introduced into the structure, they contribute by hydrogen bonding to the stiffness and clarity of the polymer. However, chain extensions of the kind just described above dilute the total polysiloxane content of the prepolymer and therefore larger amounts of such a prepolymer are required to maintain a high oxygen permeability in the final polymer.

The transparent, hard and oxygen-permeable polymers according to the invention are produced in a final synthesis step by free radical copolymerization, either in bulk or in the presence of smaller amounts of the solvent. Said synthesis step for the production of a copolymer is a method which includes reacting polysiloxane compounds with the formula

or

wherein Rlf R2, Ra,<R>b, Rc, Rd>Re, Rf>Rg>Rh>Rl><R>jf<R>k> Zi( xl'x2'yi °S v2nar the 1 claim 1 specified meanings ,

with diisocyanates of formula

wherein R4 has the meaning stated in claim 1, in the presence of a catalyst, the resulting polysiloxane-polyisocyanate prepolymers being end-capped by reacting them with a small excess of active hydrogen-containing monomers of the formula

in which

R3, Rfc, Rg and Z2 have the meanings stated in claim 1, or with allyl alcohol or methallyl alcohol or compounds of the formula

in which

R7 has the meaning stated in claim 1, so as to form the polysiloxane macromers (A) which are copolymerized with a vinyl monomer (B), selected from a mixture of a water-soluble monomer B2 and a water-insoluble monomer B^, a water-insoluble monomer Bj, or a mixture thereof, the monomers being monoolefinic, a diolefinic monomer Bxor a mixture thereof, or a mixture of monoolefinic monomers and diolefinic monomers, the monomer having the meaning stated in claim 1, using a free radical developing initiator. The polymerization is suitably carried out by heating and suitably in the presence of a free radical producing initiator, e.g. at a temperature in the range from approx. 40°C to approx. 105°C in preferred temperature ranges are between approx. 50°C and approx. 100°C. These initiators are preferably peroxides or azo catalysts which have a half-life at the polymerization temperature of at least 20 minutes. Typical suitable peroxide compounds include: isopropyl percarbonate, tert-butyl peroctoate, benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, acetyl peroxide, succinic peroxide, methyl ethyl ketone peroxide, tert-butyl peroxyacetate, propionyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxy pivalate, pelargonyl peroxide, 2 ,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, p-chlorobenzoyl peroxide, tert-butyl peroxybutyrate, tert-butyl peroxymaleic acid, tert-butyl peroxyisopropyl carbonate, bis(1-hydroxycyclohexyl)peroxide, azo compounds comprising: 2,2-azo-bis-isobutyronitrile, 2,2'-azo-bis(2,4-dimethylvaleronitrile), 1,1'-azo-bis(cyclohexanecarbonitrile), 2,2'-azo-bis( 2,4-dimethyl-4-methoxyvaleronitrile).

Other free radical-producing mechanisms can be used, such as radiation with e.g. X-rays, electron beams and UV radiation. Production of contact lens raw materials using UV radiation in the presence of a photo-initiator, such as diethoxyacetophenone, 1-hydroxycyclohexyl-phenylketone, 2,2-dimethoxy-2-phenylacetophenone, phenothiazine, diisopropyl-xanthogen disulphide, benzoin and benzoin derivatives is a preferred method.

The amount of initiator can vary from 0.002% to 1% by weight

of the monomer and the macromer, but is preferably from 0.03

to 0.3% by weight thereof.

A preferred laboratory method for producing the polymer, in the form of a cylinder, comprises filling an elastic polymer cylinder: with the preferred composition of macromers. monomers and catalyst, and reacting the mixture for approx. 2 hours at 80°C. The finished article is removed by splitting the cylinder lengthwise and stripping it away from the polymer.

Enanne.^. preferred method for producing the polymer is by irradiation with ultraviolet light in the presence of a photo-initiator and the use of plastic forms which are transparent to UV, such as forms made of polypropylene. The reaction is preferably carried out in an inert atmosphere if carried out in open forms. It is known that oxygen inhibits polymerization and causes extended polymerization time. If closed molds are used to form the article, the molds are composed of inert materials that have low oxygen permeability and non-adhesive properties. Examples of suitable mold materials are poly(tetrafluoroethylene), such as Teflon, silicone rubber, polyethylene, polypropylene and polyester, such as Mylar. Glass and metal molds can be used if a suitable mold release agent is used.

The transparent and oxygen-permeable polymers according

to the invention consists of 8-70% of the macromer (A), copolymerized with 30-92% of the vinyl comonomer component (B).

The polymers according to the invention can be adapted so that they

is suitable either as hard contact lens material or as soft contact lens material. Different comonomers and different amounts of polysiloxane macromers are required to achieve optimal performance with one or the other contact lens type.

When choosing the polysiloxane component and the vinyl monomer for a hard contact lens composition, it is naturally important to find a mixture that will give clear polymers with sufficient molecular stability and oxygen permeability. Sometimes a mixture of comonomers is advantageous

to avoid phase separation and thus opacity. It is also easier to obtain clear products with relatively low molecular weight polysiloxanes than with high molecular weight polysiloxane. Polysiloxanes with a short chain length between crosslinks also give harder, more molally stable polymers, but their oxygen permeability is reduced compared to polysiloxanes with longer chain length and therefore lower crosslink density. With a judicious choice of monomer(s) and polysiloxane macromers, it is possible to adapt to a consider-

equal degree in physical values and oxygen permeability of the silicone polymers.

For the manufacture of hard contact lenses, the preferred polymer comprises the cross-linked copolymerization product of (A) from about 15 to approx. 35% by weight of a polysiloxane macromer, and (B) from approx. 80 to approx. 65% by weight of a mixture

of water-insoluble monomers (B^), of water-soluble monomers (B2), and a diolefinic monomer (Bx), wherein, based on growth % of the total weight of monomers, B^ is from ca. 60 to approx. 95%, B2s from approx. 15 to approx. 0%, and B^ is from approx. 25 to approx. 5%. The preferred water-insoluble monomers B1 are methyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate or mixtures thereof. The preferred water-soluble monomers B2 are 2-hydroxyethyl methacrylate, N,N-dimethylacrylamide, acrylic acid, methacrylic acid or N-vinyl-2-pyrrolidone or mixtures thereof. The preferred diolefinic monomer B1 is neopentylene glycol diacrylate, ethylene glycol dimethacrylate or the reaction product of 1 mole of isophorone diisocyanate and 2 moles of 2-hydroxyethyl methacrylate.

For making soft contact lenses, the preferred polymer crosslink copolymerization product of (A) comprises from about 40 to approx. 60% by weight of a polysiloxane macromer, and (B) from approx. 60 to approx. 40% by weight of a mixture of water-insoluble monomer (B^, of water-soluble monomer (B2), and of a diolefinic monomer (B^), wherein, based on the weight% of the total weight of monomers, B ^is from approx.

75 to approx. 100%, B2er- from approx. 25 to approx. 0%, and Bxer from approx. 5 to approx. 0%. The preferred water-insoluble monomers (B^) are ethyl acrylate or methacrylate, n-butyl acrylate or methacrylate, n-hexyl acrylate or methacrylate, 2-ethylhexyl acrylate or methacrylate, n-octyl acrylate or methacrylate, n-decyl acrylate or methacrylate, or mixtures thereof or with mixtures thereof with methyl or isobornyl-meth-

acrylate. The preferred water-soluble monomers (B2)

and diolefinic monomers (Bx) are those indicated above for making hard contact lenses.

An example of a preferred polymer for the manufacture of

a hard contact lens comprises (A) 30% by weight of the polysiloxane of structure A2, where R4 is a diradical derived from isophorone diisocyanate, Z, and Zp are each -0-, and y„ is 2, and 70% by weight of monomer (B) wherein, based on % by weight of total monomers, B is 71.4% of methyl methacrylate, B2 is 5.7% of 2-hydroxyethyl methacrylate, and Bx is 22.9% of neopentylene glycol diacrylate.

An example of a preferred polymer for making a soft contact lens comprises (A) 50% by weight of the polysiloxane of structure A2 where R4 is a diradical derived from isophorone diisocyanate, Z-^ and Z2 are each -O-, and y2 is 2, and 50% by weight of monomers (B) in which B^ is 80% of a 50/50 mixture of methyl methacrylate/2-ethylhexyl acrylate and B2 is 20%

of 2-hydroxyethyl methacrylate.

Although the invention is directed primarily to the production of hard, dimensionally stable contact lenses, it is within the scope of the invention to use any of the above-mentioned monomers to produce strong, 02-permeable polymers with a wide range of physical values, from hard and rigid until rubbery and soft. Such soft polymers are e.g. suitable for dressings, or as soft contact lenses, especially when treated by any of the commonly used methods used to increase the wettability of hydrophobic surfaces, such as plasma treatment and beam refining and oxidation.

Due to their good tissue compatibility and oxygen permeability and strength and elasticity, the polymers according to the present invention are particularly suitable for use as intramuscular and subcutaneous implants in warm-blooded animals and as contact lens material. For the same reasons, the materials according to the present invention can be adapted to substitute blood vessels or extracorporeal shunts.

The following examples specifically determine oxygen permeability (02.DK) by measuring dissolved oxygen permeability at 35°C with a polarographic electrode in an air-saturated aqueous environment and are expressed in units

Wetting ability is determined by measuring the contact angle of an n-octane trawl that had risen to the lower surface of a 1 mm thick test sheet dipped in octane saturated with distilled water at 36°C. In this measurement, high numbers indicate high wetting ability.

Hardness is determined using a shore-D durometer

on polished surfaces of center-cut buttons with a diameter of 10 mm and a height of 8 mm.

Example 1.

Production of polysiloxane macromers.

A 1-liter 3-necked flask equipped with a mechanical stirrer, thermometer, condenser, and nitrogen inlet is filled with 186.6

g (0.03 mol) of polydimethylsiloxane-triol (DOW CORNING liquid 1248), which had been stripped of volatiles by passing it through a coated-film evaporator. 21.0 g (0.0945 mol) of 1-isocyanatemethyl-5-isocyanate-1,3,3-trimethyl-cyclohexane (isophorone diisocyanate, IPDI) are then added together with 0.025 g of dibutyltin dilaurate as catalyst. The mixture is then stirred under nitrogen on a temperature-controlled water bath at 50°C for 5 hours. At this time, the NCO content as determined by titration had fallen to 1.94% (2.00% theoretical).

Next, 169.4 g of polydimethylsiloxane-triisocyanate prepolymer as prepared above is diluted with 10.2 g of 2-hydroxyethyl methacrylate (HEMA) and stirred under nitrogen at room temperature until all NCO groups have been reacted as determined by the absence of the isocyanate band from the infrared spectrum. The resulting product consists of >99.9% polysiloxane-terminated methacrylate and a minor amount of HEMA-terminated IPDI indicating that some chain extension had occurred. This was also confirmed by gel permeation chromatography.

Examples 2-17.

Preparation of polymer samples.

30 g each of the polysiloxane macromer as prepared according to Example 1 are mixed with comonomers in the conditions shown in Table 1. 0.06 g (0.2%) 1-hydroxycyclohexyl-phenylketone, (UV)-initiator S) is added and each mixture is thoroughly degassed and then stored under nitrogen. A portion of each mixture is used to make 0.1

mm thick films between silane-treated glass plates, 0.1

mm thick MYLAR (polyester film from DuPont) is used as a spacer and the mold is held together with clamps. The molds are exposed to UV light from a "Black Light Blue" (SYLVANIA) lamp for 3 hours, after which time the polymer is removed from the mold and used for oxygen permeability measurements.

In the same way, a 1 mm thick sheet is cast from each monomer-macromer mixture and used to determine wetting ability.

Yet another portion of each monomer-macromer mixture is filled with a fixed-volume syringe into cylindrical polypropylene molds of 14 mm diameter and 8 mm height and closed with a loose-fitting, convex polypropylene cap. The molds are placed on a rack and irradiated in a nitrogen-flushed box using the lamps as described above, first below only until the mixture is fully formed (15 minutes) and then from above downwards for a total of 3 hours. Then the shapes are opened and the poly button is removed. Several buttons are cut in halves, both parallel and normal to the round surface, and the cut surfaces are polished to measure hardness.

Values in the following table show the effect of selected comonomers on C^-DK, wettability and hardness. These polymers have Young's modulus values of >1(GPa). The following examples show the effect of polysiloxane macromer content on G^DK and wettability.

Examples 18-26.

Following the procedure described in the previous Examples 2-17, the macromer as prepared in Example 1 is mixed with various amounts of monomers as shown in Table 2, and blend-polymerized into 0.1 mm and 1.0 mm thick films. The polymers test as described for oxygen permeability and wettability.

Examples 27-29.

The following examples show the effect of using

a hydrophilic comonomer (dimethylacrylamide). The same procedures as described in Examples 18-26 are followed.

Examples 30-34

The following examples show the effect of additional cross-linking agents on G^DK, wettability and hardness.

By following the procedure described in Examples 2-17, the macromer as prepared in Example 1 is mixed with comonomers in proportions as shown in the table. The mixtures were polymerized and tested as described.

Examples 35-38.

The procedure from example 1 is repeated, but the amount of isophorone diisocyanate (IPDI) is increased from 0.0945 mol (corresponding to a 5% molar excess of NCO/OH) to

0.105 (16.7% molar excess of NCO) ex: 35 0.166 (84.4% molar excess of NCO) ex: 36 0.243 (170.0% molar excess of NC0)ex: 37 0.335 (272.2% molar excess of NCO) ex: 38.

After reacting the NCO-terminated prepolymer with HEMA for a mixture of 30 parts polysiloxane-terminated methacrylate, 4 parts HEMA, and 1, 5, 10, and 16 parts of the reaction product of 2 mol HEMA and 1 mol (IPDI (IPDI-dihema), as determined by gel permeation chromatography.

The mixtures are diluted with methyl methacrylate and cast in the form of clear buttons, sheets and film with the following properties:

The following examples show the utility of the polysiloxane-urethane methacrylate in the production of clear and soft oxygen permeable polymers (with Young's Modulus 1.) for use as soft contact lenses.

Examples 39. 44.

The polysiloxane macromer from example 1 is diluted with different comonomers and 0.1% UV initiator A and polymerized by exposure to UV as described in examples 2-17. Compositions and properties are shown below.

Examples 45-48.

The polysiloxane macromer from example 1 is diluted with various comonomers and 0.2% UV initiator A and polymerized by exposure to UV as described in examples 2-17. Clear polymers are obtained, whose compositions and properties are shown below:

The following examples show the applicability of active hydrogen-containing monomers other than HEMA for the production of the polysiloxane prepolymer.

Examples 49-55.

The procedure from example 1 is repeated, but instead of HEMA, equivalent amounts of other active hydrogen-containing vinyl monomers are used to end the NCO-terminated polysiloxane prepolymer. Completion of the final termination step is checked with IR spectroscopy. In this way, the following vinyl-terminated polysiloxanes are produced as clear, viscous liquids.

The following examples show the applicability of polysiloxanes with methacrylic, vinyl ether and fumarate unsaturation in the production of clear, hard and G₂-permeable polymers.

Examples 56-60.

The vinyl-terminated polysiloxanes according to Examples 45-

47 is diluted with monomers and polymerized in the form of clear films and buttons, using 0.02% UV initiator A as initiator. The compositions and their physical properties are listed in the following table.

Example 61.

Following the procedure from Example 1, polydimethylsiloxane triol (DOW CORNING liquid 1248) is end-capped with isophorone diisocyanate. A 10% molar excess of methacrylic acid is added together with 0.05% cobalt naphthenate. CO2 is evolved and the mixture is kept at 50°C for 6 hours after which time the % value of NCO has fallen to the next 0. The mixture is diluted with 70% methyl methacrylate, 0.1% UV initiator A is added and polymer sheets and films are prepared as described in Example 2. The polymer is cloudy-white, has an O2DK of 68 and an octane/water contact angle of 103°.

Example 62.

By following the procedure of Examples 1 and 2, a polymer is prepared using 2,2,4(2,4,4)-trimethylhexane-1,6-diisocyanate instead of IPDI. A polymer with essentially identical properties to that from example 2 is obtained.

The following examples show the applicability of fluorinated comonomers in the production of clear, oxygen permeable polymers according to the invention.

Examples 63-68.

By following the procedure from examples 1 and 2, is prepared

the following polymers and their oxygen permeability are measured. The abbreviation MA in the fluorinated comonomer means methacrylate.

All samples are completely clear.

The following example shows that the clarity of polymers from Examples 63-68 is an unexpected result as analogous compositions containing no silicone give incompatible mixtures and weak, opaque polymers:

Example 69.

Example 63 is repeated, but the siloxane macromer from example

1 is replaced with an analogous macromer which is obtained by reacting 1 mol of polytetramethylene oxide diol (2000 MW) with 2 mol of isophorone diisocyanate, followed by end termination with excess HEMA. An incompatible mixture is obtained which phase-separates by settling and underpolymerisation. The polymer sheet formed is opaque, brittle and very weak.

The following examples show the use of other polysiloxanes in the production of the present polymers.

Example 70.

By following the procedure from example 1, 21.7 g are converted

(0.025 m) of polydimethylsiloxane diol (DOW CORNING .liquid Q4-3557) with 11.7 g (0.0526 m) of isophorone diisocyanate. After stirring under nitrogen for 5 hours at 50°C, the NCO content drops to 6.80% (6.90% theoretical).

Then 22.3 g of this polydimethylsiloxane-diisocyanate prepolymer is diluted with 5.2 g of 2-hydroxyethyl methacrylate (HEMA) and stirred at room temperature under nitrogen until all the NCO has been converted. The clear, methacrylate-end-capped polysiloxane is stored cold under nitrogen. It consists of 98.2% methacrylate end-capped polysiloxane and 1.8% unreacted

HOME.

Next, 20 g of the thus produced polysiloxane-dimethylacrylate prepolymer is diluted with 20 g of methyl methacrylate.

0.4 g of UV initiator A is mixed in and the mixture is degassed in a vacuum. Using the procedure as described in example a, samples are cast as 0.1 and 1.0 mm thick films and sheets, and in the form of cylindrical buttons of 14 mm diameter. The clear polymer has the following properties.

Example 71.

Following the procedure of Example 1, 28.98 g (0.015 m) of a polydimethylsiloxane (PDMS)-polyethylene oxide (PEO) block copolymer having the structure (PEO-PDMS-PEO, having an equivalent weight of 966 (DOW CORNING liquid Q4-3667) with 6.80 g (0.0306 m) of isophorone diisocyanate (PIDI). After stirring under nitrogen for 1 hour at 50°C, the NCO content drops to 3.87% (3.65% theoretical) (or 0.330 equivalents of -NCO).

Next, 28.72 g of this NCO-terminated prepolymer is mixed with 6.10 g (0.033 m) of t-butylaminoethyl methacrylate (BAEM) and stirred at room temperature under nitrogen until all the NCO has been converted. The end of the turnover is checked with IR spectroscopy. The clear, viscous-methacrylate-end-capped PDMS prepolymer is diluted with 35.2 g of methyl methacrylate and 0.14 g of UV initiator A is added. After thorough mixing, the mass is cast in the form of sheets and films and polymerized by exposure to UV light.

The clear and tough polymer consists of 50% methacrylate-terminated polysiloxane prepolymer and 50% methyl methacrylate, swells to equilibrium it contains 9% water and has the following oxygen permeability: 02-DK = 12.3 (9% I^ Q);

24.3 (dry).

Example 72.

Following the procedure of Example 1, 41.0 g (0.015 m) of a polydimethylsiloxane (PDMS) dithio equivalent weight 1367 (DOW CORNING X2-8024) is reacted with 6.8 g (0.036

m) IPDI, using 0.02 mg of triethylamine as catalyst. After stirring under nitrogen for 1-1/2 hours at 24-28°C, the NCO content falls to 2.83% (2.74% theoretical).

Next, 44.22 g of this NCO-end terminated prepolymer is mixed with 5.96 g of t-butylaminoethyl methacrylate and stirred at room temperature under nitrogen until all the NCO has been converted. The end of the turnover is checked with IR spectroscopy. The clear, viscous methacrylate end-capped PDMS prepolymer is diluted with 0.5 g of HEMA and 115 g of methyl methacrylate and 0.1 g of UV initiator A are added. After thorough mixing, the mixture is cast in the form of sheets and films and polymerized by exposure to UV light.

The clear polymer consisting of 69% methacrylate-terminated polysiloxane prepolymer, 30.7% MMA and 0.3% HEMA has the following properties:

The following example shows the synthesis of a polymer with a chain-extended polysiloxane.

Example 73.

Following the procedure of Example 1, 54.66 g (0.02 m) of a polydimethylsiloxane (PDMS) dithiol of equivalent weight 1367 (DOW CORNING X8024) is reacted with 2.10 g (0.01 m) 2.2 ,4-trimethylhexane-1,6-diisocyanate (TMDI) using 0.020 g of triethylamine as catalyst. After stirring overnight at room temperature (24°C) and below , an IR scan shows that all isocyanate groups have been reacted, indicating that chain extension with 2 molecules of polydimethylsiloxane dithiol with 1 molecule of TMDI has taken place.

56.8 g (0.01 m) of this chain-extended dithiol is reacted with 4.53 g (0.0204 m) of IPDI. The reaction mixture is stirred at 24°C for 1 1/2 hours, by which time the -NCO content has fallen to 1.49% (1.43% theoretical). 57.2 g of this NCO-terminated prepolymer is mixed with 3.75 g of t-butyl-amino-ethyl methacrylate and stirred at 24°C until all the NCO has been converted as checked by IR spectroscopy.

15 g of the methacrylate-terminated PDMS prepolymer is mixed with 35 g of methyl methacrylate and 0.05 g of UV initiator A. The mixture is cast in the form of sheets and films or buttons and polymerized by exposure to UV light as described in example 2. The slightly cloudy polymer has the following properties:

The following examples demonstrate the superiority of polymers containing urethane groups over polymers containing no urethane groups.

Examples 74-76.

Polydimethylsiloxane methacrylates bearing methacrylate groups attached to the main chain and bound to it by carbinol ester linkages and which are available from PETRAPCH Chem.. Co, under the code:

dilute to 30% with 4% HEMA and 66% cyclohexyl methacrylate. To each 0.1% UV initiator A is added and the mixtures are polymerized by exposure to UV in the form of 0.1 mm and 1.0 mm thick films and sheets. The results are shown in the following table.

Methacrylate esters prepared by esterification of polydimethylsiloxane triol (1248) with methacryloyl chloride and which are therefore similar to the polysiloxane methacrylate according to example 1 with the exception of the absence of urethane groups, likewise give opaque and weak polymers when formulated and polymerized as described above ( e.g. 76).

The following example shows the applicability as well as the superiority of hard contact lenses made from the polymers according to the invention, over previously known materials.

Example.

Round polymer buttons from Examples 30 and 33, molded in a manner as described in Example 2, of 15 mm diameter and 8

mm height, made into contact lens shapes by turning and polishing using conventional techniques in hard contact lens manufacturing. Suitability for machining, surface gloss, hardness, scratch resistance and target stability and clarity of all samples are excellent and no change in the base curve upon hydration was observed.

A polymer button from example 30 was machined to

a form to fit the electrode of an oxygen permeability apparatus. C^-permeability is measured and compared with previously known materials which also have good target stability and are offered as oxygen permeable, hard contact lens material:

None of the other synthetic products for the production of Si-containing contact lenses provide materials with such high oxygen permeability as can be achieved with polymers according to the invention, while at the same time maintaining the necessary hardness for machining and polishing.

Claims (16)

1. Polymer suitable for the manufacture of contact lenses, characterized in that it consists of a cross-linked polymerization product of (A) from 15 to 60% by weight of a linear or branched polysiloxane macromer having a molecular weight of from 400 to 100,000, as measured by end group analysis or gel permeation chromatography, wherein the macromer contains at least two terminal or pendant polymerizable olefinic groups per each 5000 molecular weight units of polysiloxane, the groups being connected to the polysiloxane with at least two urethane, thiourethan, urea or amide bonds, the macromer having the structure A^ or A^ or wherein Rj is a linear or branched alkylene group of 2-6 carbon atoms or a polyoxyalkylene group of structure G wherein R3 is hydrogen or methyl, and n is an integer from 1-50, R2, Ra, Rb, Rc, Rd, Re, Rf, Rg, Rh, Ri, Rj and Rk are methyl, X and X2 are whole numbers from 1-500, with the proviso that the sum of X^plus X2 is 7 to 100, y^means 0 to 14 and Y2 means 1 to 13, with the proviso that the ratio of X} t- X2or X-^ + X2 is not greater than 70, ~ Yi + 2~ Y2+ 1 X is a diradical of formula C wherein Zj is oxygen, sulfur or NR 5 , and R 5 is hydrogen or lower (C 1 -C 4 ) alkyl, Z is joined to R 5 ; and R 4 is the divalent radical formed by removing NCO groups from an aliphatic or cycloaliphatic diisocyanate; Y is a group with formula wherein R 5 is hydrogen, methyl or -COOR 5 , wherein R 5 is hydrogen or lower (C 1-4 )-alkyl; Z2 means oxygen or -NR5-, and R7 and Rg are linear or branched alkylene with 2-10 carbon atoms, and of from 85 to 40% by weight of a vinyl monomer (B) consisting of a mixture of a water-soluble monomer B2 and a water-insoluble monomer B^, or a water-insoluble monomer or a mixture thereof, the monomers being monoolefinic, or a diolefinic monomer Bx or a mixture thereof, or a mixture of the monoolefinic and diolefinic monomers with from 85 to 100 wt-# of the total monomers such as water insoluble, where the monoolefinic monomers B^ are selected from acrylates or methacrylates of formula CH2=CR3C00Ri2» acrylamides or methacrylamides of formula CH2=CR3C0NHR^2, maleates or fumarates of formula R^20C0CH=CHC00R^2» itaconates of formula<R>i200CC( =CH2)CH2C00R12>vinyl esters of the formula Rl2c00CH=CH2 or vinyl ethers of the formula C02=CH0R12, wherein R3 means hydrogen or methyl, and R^2 is a linear or branched aliphatic, cycloaliphatic or aromatic alkyl group with from 1 to 21 carbon atoms, and which may contain ether -or thioether bonds or -CO group, or means a heterocyclic substituted alkyl group containing oxygen, sulfur or nitrogen atoms, or a polypropylene oxide or poly-n-butylene oxide group with from 2-50 recurring alkoxy units or means perfluorinated alkyl groups with from 1-12 carbon atoms, or means acrylonitrile, styrene or α-methylstyrene, and the olefinic monomers B2 are selected from acrylates or methacrylates with the formula CH2=CR3C00Rj3, acrylamide r or methacrylamides of the formula CH2=CR3C0NHRj4or CCH2=CR3C0N(R5)2, maleates or fumarates of the formula Rl30C0CH=CHC00R13, vinyl ethers of the formula CH2=CH0Ri3, or N-vinyllatamers, in which R3 is hydrogen or methyl, R5 is hydrogen or lower(0^ -4)-alkyl, R 13 is a hydrocarbon residue with 1-10 carbon atoms, substituted with one or more water-solubilizing carboxy, hydroxy or tert.-amino groups, or a polyethylene oxide group with from 2 to 100 recurring units, and R 4 has the same meaning as Rl3 or R5, and the diolefinic monomers Bx selected from acrylates or methacrylates of allyl alcohol, diacrylates or dimethacrylates of straight or branched alkylene glycol with 2-6 carbon atoms, of poly(ethylene oxide) glycol, of poly(propylene oxide) glycol, of poly(n -butylene oxide )glycol, of thiodiethylene glycol, of neopentylene glycol, of trimethylolpropane or of pentaerythritol, or the reaction product formed by reacting 1 mol of a dl- or tri-isocyanate with the structure 0CN-R4-(NC0)v, where R4 has the above meaning, and v means 1 or 2, with 2 or 3 moles of a hydroxyalkyl acrylate or methacrylate. 2. Polymer according to claim 1, characterized in that in the polysiloxanes with the structure A or A2, Rj means the alkylene with 3 or 4 carbon atoms, + x2 means 10 to 100, yj means o to 2, y2 means 1 to 3, R4 is a diradical of an aliphatic or cycloaliphatic diisocyanate with 6 to 10 carbon atoms, and that in the group with formula (D) R6 means hydrogen, R8 means ethylene and Z2 means -0~or~NC(CH3)3-. 3. Polymer according to claim 2, characterized in that the polysiloxane has the structure A2, R4 is the diradical derived from isophorone diisocyanate, Z and Z2 are each -0-, and y2 is 1 or 2. 4. Polymer according to claim 1, characterized in that the water-insoluble monomer is selected from the group consisting of methyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, hexafluoroisopropyl methacrylate or mixtures thereof. 5. Polymer according to claim 1, characterized in that component B contains 1 to 25% based on the total weight of the used monomer component B of a diolefinic monomer Bx. 6. Polymer according to claim 1, characterized in that component B is a mixture of methyl methacrylate and 1 to 25% by weight of the total monomer of neopentylene glycol diacrylate, ethylene glycol dimethacrylate or the reaction product of 1 mol of isophorone diisocyanate and 2 mol of 2- hydroxyethyl methacrylate. 7. Polymer according to claim 1, characterized in that the water-insoluble monomer is a mixture of vinyl acetate and dimethyl maleate in a 2/1 to 5/1 molar ratio, plus methyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, or hexafluoroisopropyl methacrylate or mixtures of this. 8. Polymer according to claim 1, characterized in that the water-insoluble monomer Bj is selected from the group consisting of 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-butyl acrylate, n-butyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-decyl acrylate, n-decyl methacrylate , perfluoroalkyl (C 1 -C 10 )-substituted alkyl acrylate or -methacrylate, or mixtures thereof. 9. Polymer according to claim 1, characterized in that the water-soluble monomer B2 is selected from the group consisting of 2-hydroxyethyl methacrylate, N,N-dimethylacrylamide, acrylic acid, methacrylic acid or N-vinyl-2-pyrrolidone. 10. Polymer according to claim 1, characterized in that it comprises (A) from 15 to 35 wt-# of a polysiloxane macromer of structure A2 in which R4 is the diradical derived from isophorone diisocyanate, Zj and Z2 are each -0-, and y2 is 1 or 2, and the others symbols have the meaning given in claim 1, and (B) from 85 to 65 wt% of a mixture of a water-insoluble monomer (B^) and a water-soluble monomer (B2), and of a diolefinic monomer (Bx ), wherein, based on weight-* of the total weight of monomers, Bjer from 60 to 95* of a water-insoluble monomer selected from the group consisting of methyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, and mixtures thereof, B2 is from 15 to 0* of a water-soluble monomer selected from the group consisting of 2-hydroxyethyl methacrylate, N,N-dimethylacrylamide, acrylic acid, methacrylic acid, N-vinyl-2-pyrrolidone and mixtures thereof, and Bs is from 25 to 5* of a diolefinic monomer selected from the group consisting of neopentylene glycol -diacrylate, ethylene glycol dimethacrylate, and the reaction product of 1 mole of isofuron diisocyanate with 2 moles of hydroxyethyl methacrylate. 11. Polymer according to claim 1, characterized in that it consists of a polymerization product of (A) from 40 to 60 weight-* of the polysiloxane macromer of structure A2 in which R4 is the diradical derived from isophorone diisocyanate, Zj and Z2 are each -0-, and y2 is 1 or 2, and the other symbols have the meaning stated in claim 1, and (B) from 60 to 40 weight-* of a mixture of water-insoluble monomer (Bj), a water-soluble monomer (B2), and of a diolefinic monomer (Bx), wherein , based on weight-* of the total weights of monomers, contains from 75 to 100* of a water-insoluble monomer selected from the group consisting of ethyl acrylate or methacrylate, n-butyl acrylate or -methacrylate, n-hexyl acrylate or - methacrylate, 2-ethylhexyl acrylate or -methacrylate, n-octyl acrylate or -methacrylate, n-butyl acrylate or clay methacrylate, and mixtures thereof, and with mixtures thereof with methyl or isoburnyl methacrylate, B2 consists of 25-0* of a water-soluble monomer selected from the group consisting of 2 -hydrocyethyl methacrylate, N,N-dimethylacrylamide , acrylic acid, methacrylic acid, N-vinyl-2-pyrrolidone and mixtures thereof, and Bx consists of from 5 to 0* of a diolefinic monomer selected from the group consisting of neopentylene glycol diacrylate, ethylene glycol dimethacrylate, and the reaction product of 1 mole of isophorone dilocyanate and 2 moles of 2-hydroxyethyl methacrylate. 12. Process for the production of a copolymer, characterized by the addition of polysiloxane compounds of formula or wherein RltR2, Ra.<R>b'Rc• Rd>Re. Rf. Rg>Rh. Ri- Rj ><R>k> zl. xl f<x>2'vl °S<y>2when the 1 claim 1 stated meanings, with diisocyanates of formula OCH-R4-NCO wherein R4 has the meaning stated in claim 1, in the presence of a catalyst, the resulting polysiloxane-polyisocyanate prepolymers being end-capped by reacting them with a small excess of active hydrogen-containing monomers of the formula in which R 3 , R 0 , R 8 °S z 2 are the meanings given in claim 1 with allyl alcohol or methallyl alcohol or compounds of formula in which R7 has the meaning stated in claim 1, so as to form the polysiloxane macromers (A) which are copolymerized with a vinyl monomer (B), selected from a mixture of a water-soluble monomer B2 and a water-insoluble monomer, a water-insoluble monomer, or a mixture thereof, as the monomers are monoolefinic, a diolefinic monomer Bx or a mixture thereof, or a mixture of monoolefinic monomers and diolefinic monomers, wherein the monomer has the meaning stated in claim 1, where a free radical developing initiator is used. 13. Method according to claim 12, characterized in that the copolymerization is effected by free-radical copolymerization in bulk or in the presence of a solvent. 10. Method according to claim 13, characterized in that the free-radical copolymerization is effected by heat or irradiation. 15. Method according to claim 14, characterized in that the heat copolymerization is carried out at a temperature from 40 to 105°C in the presence of a free-radical developing initiator. 16. Method according to claim 14, characterized in that the copolymerization is effected by UV irradiation in the presence of a photoinitiator.